HDO of Methyl Palmitate over Silica-Supported Ni Phosphides: Insight into Ni/P Effect

Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH₃COO)₂) and ((NH₄)₂HPO₄) as a precursor. The Ni_xP_y/SiO₂ catalysts were characterized using chemical analysis N₂ physisorption, XRD, TEM, ³¹P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO) was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h⁻¹. The Ni/P ratio was found to affect the nickel phosphide phase composition, PO_x groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of PO_x groups’ content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis), we proposed that the enhancement of acid PO_x groups’ content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis. View Full-Text